CA1324247C - Precipitated silicas, process for producing same and their use - Google Patents
Precipitated silicas, process for producing same and their useInfo
- Publication number
- CA1324247C CA1324247C CA000552383A CA552383A CA1324247C CA 1324247 C CA1324247 C CA 1324247C CA 000552383 A CA000552383 A CA 000552383A CA 552383 A CA552383 A CA 552383A CA 1324247 C CA1324247 C CA 1324247C
- Authority
- CA
- Canada
- Prior art keywords
- reaction medium
- slllca
- preclpltated
- wlth
- precipitated silica
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000000034 method Methods 0.000 title claims abstract description 28
- 238000001556 precipitation Methods 0.000 claims abstract 6
- 239000000725 suspension Substances 0.000 claims abstract 6
- 238000005498 polishing Methods 0.000 claims abstract 2
- 230000008719 thickening Effects 0.000 claims abstract 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 35
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 30
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 11
- 239000000606 toothpaste Substances 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 5
- 229910052681 coesite Inorganic materials 0.000 claims description 3
- 229910052906 cristobalite Inorganic materials 0.000 claims description 3
- 229910052682 stishovite Inorganic materials 0.000 claims description 3
- 229940034610 toothpaste Drugs 0.000 claims description 3
- 229910052905 tridymite Inorganic materials 0.000 claims description 3
- 239000003513 alkali Substances 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims description 2
- 239000007787 solid Substances 0.000 claims description 2
- 239000000377 silicon dioxide Substances 0.000 claims 17
- 239000012429 reaction media Substances 0.000 claims 15
- 229910052910 alkali metal silicate Inorganic materials 0.000 claims 8
- 239000002253 acid Substances 0.000 claims 6
- 238000006243 chemical reaction Methods 0.000 claims 3
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims 2
- 235000012239 silicon dioxide Nutrition 0.000 claims 2
- 229910052938 sodium sulfate Inorganic materials 0.000 claims 2
- 235000011152 sodium sulphate Nutrition 0.000 claims 2
- 239000007832 Na2SO4 Substances 0.000 claims 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims 1
- 239000004115 Sodium Silicate Substances 0.000 claims 1
- 230000015572 biosynthetic process Effects 0.000 claims 1
- 238000007865 diluting Methods 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 claims 1
- 239000002244 precipitate Substances 0.000 claims 1
- 230000001376 precipitating effect Effects 0.000 claims 1
- 229910052911 sodium silicate Inorganic materials 0.000 claims 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical group [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims 1
- 239000007921 spray Substances 0.000 claims 1
- 230000000694 effects Effects 0.000 abstract description 8
- 239000002245 particle Substances 0.000 abstract 2
- 238000004140 cleaning Methods 0.000 abstract 1
- 239000000551 dentifrice Substances 0.000 abstract 1
- 238000001035 drying Methods 0.000 abstract 1
- 238000001914 filtration Methods 0.000 abstract 1
- 238000000227 grinding Methods 0.000 abstract 1
- 239000000203 mixture Substances 0.000 abstract 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 20
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 15
- 238000005259 measurement Methods 0.000 description 10
- 239000010949 copper Substances 0.000 description 9
- 229910052742 iron Inorganic materials 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- CMDGQTVYVAKDNA-UHFFFAOYSA-N propane-1,2,3-triol;hydrate Chemical compound O.OCC(O)CO CMDGQTVYVAKDNA-UHFFFAOYSA-N 0.000 description 6
- 241001163743 Perlodes Species 0.000 description 5
- 230000003247 decreasing effect Effects 0.000 description 5
- 239000000376 reactant Substances 0.000 description 5
- 239000006072 paste Substances 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- -1 as for example Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 229910021653 sulphate ion Inorganic materials 0.000 description 2
- 241001465754 Metazoa Species 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 208000036366 Sensation of pressure Diseases 0.000 description 1
- 239000008346 aqueous phase Substances 0.000 description 1
- 230000001609 comparable effect Effects 0.000 description 1
- 210000003298 dental enamel Anatomy 0.000 description 1
- 239000003599 detergent Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 235000014571 nuts Nutrition 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 235000011149 sulphuric acid Nutrition 0.000 description 1
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K8/00—Cosmetics or similar toiletry preparations
- A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
- A61K8/19—Cosmetics or similar toiletry preparations characterised by the composition containing inorganic ingredients
- A61K8/25—Silicon; Compounds thereof
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
- A61Q11/00—Preparations for care of the teeth, of the oral cavity or of dentures; Dentifrices, e.g. toothpastes; Mouth rinses
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
- C01B33/187—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by acidic treatment of silicates
- C01B33/193—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by acidic treatment of silicates of aqueous solutions of silicates
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/11—Powder tap density
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/12—Surface area
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/14—Pore volume
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/19—Oil-absorption capacity, e.g. DBP values
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/22—Rheological behaviour as dispersion, e.g. viscosity, sedimentation stability
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
- C01P2006/82—Compositional purity water content
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/90—Other properties not specified above
Landscapes
- Health & Medical Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Inorganic Chemistry (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Animal Behavior & Ethology (AREA)
- Organic Chemistry (AREA)
- Epidemiology (AREA)
- Birds (AREA)
- Oral & Maxillofacial Surgery (AREA)
- Silicon Compounds (AREA)
- Cosmetics (AREA)
- Chemical Vapour Deposition (AREA)
- Dental Preparations (AREA)
- Detergent Compositions (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A process for producing silicas having a cleaning, polishing and thickening effect and being intended for use as dentifrices. This process is characterized in that the sili-cas obtained in a conventional manner by precipitation and having varying particle sizes and particle densities are homo-geneously mixed with each other in the suspension phase and that the mixtures are further treated in the usual manner by filtering, drying and grinding.
A process for producing silicas having a cleaning, polishing and thickening effect and being intended for use as dentifrices. This process is characterized in that the sili-cas obtained in a conventional manner by precipitation and having varying particle sizes and particle densities are homo-geneously mixed with each other in the suspension phase and that the mixtures are further treated in the usual manner by filtering, drying and grinding.
Description
~L 3 ~ ~t ~
The present Inventlon relates to preclpltated slll-cas, a process for thelr productlon and to thelr use In tooth pastes.
Syn~hetlcally produced preclpltated slllcas havo been of great Importance as a component of dentlfrlces for many years. They are very pUre, toxlcologlcally unobJectlon-able and compatlble wlth the other substances contalned In tooth pastes, as for example, glycerol, sorbltol, thlckeners, detergents, dyes and aromatlc substances and, when requlred, soluble fluorlne compounds.
Synthetlc preclpltated slllcas are produced by pre-clpltatlon from alkall-slllcate solutlons wlth aclds In a stlrrlng process, by fllterlng the suspenslon off, washlng, drylng and grlndlng. The preclpltatlon process provldes the posslblllty of readlly predetermlnlng Important propertles, such as partlcle dlameter, partlcle shape and partlcle denslty or hardness by operatlons In the flocculate phase.
The present Inventlon provldes a process for the productlon of cleanlng, pollshlng and thlckenlng preclpltated slllcas for dentlfrlces In whlch the slllcas of varylng partl-cle slze and partlcle denslty obtalned In the current manner by preclpltatlon are homogeneously mlxed wlth each other In the suspenslon phase and the mlxtures are further treated In a conventlonal manner by fllterlng, washlng, drylng and grlndlng.
The present Inventlon also provldes a preclpltated slllca whlch Is characterlzed by the followlng physlcal-cheml-cal characterlstlc data:
loss on drylng (DIN 53198) X 3 - 7-conductlvlty at 25C
(4% suspenslon) ~ S 400 - 800 pH vzlue (5X accordlng to DIN 53200) 6 - 7 `` ~ 3 h ~ 2 ~L, BET surface area (DIN 66131) sqm/g 130 - 150 tamped denslty (DIN 53194) g/lItre 100 - 150 macropore volume D ~ 30 nm ml/g 3.2-4.0 (~ccordln~ to the H~ pr~sur~ mcthod) oll absorptlon accordlng to Gardner ml/100 9 180 - 200 water retentlon value X 76 - 79 Cu abraslon mg 5 - 14 RDA abraslon 35 - 100 REA abraslon 40 - 90 scratches few to very few vlscoslty mPas 5000-10000 (In a 16X glycerol-water dlsperslon 1:1, splndle D wlth hellpath) Fe content p.p.m. 240-280.
The present Inventlon also provldes a process for produclng the preclpltated slllca whlch Is characterlzed by the followlng physlcal-chemlcal characterlstlc data:
loss on drylng (DIN 53198) % 3 - 7 conductlvlty at 25C ~ S 400 - 800 (4X suspenslon) pH value (5% accordlng to DIN 53200) 6 - 7 BET surface area (DIN 66131) sqm/g130 - 150 tamped denslty (DIN 53194) g/lItre100 - 150 macropore volume D , 30 nm ml/g 3.2-4.0 (accordlng to the Hg pressure method) oll absorptlon accordlng to Gardner ml/lOOg 180 - 200 water retentlon value % 76 - 79 Cu abraslon mg 5 - 14 RDA abraslon 35 - 100 REA abraslon 40 - 90 scratches few to very few vlscoslty ~ mPas 5000-10000 (In a 16% glycerol-water dlsperslon 1:1, splndle D wlth helIpath) Fe contcnt p.p.m. 240 - 280 In whlch process flrstly a thlckenlng preclpltated slllca sU
penslon IS produced by reactlng an alkall-slllcate solutlon wlth an acld whlle avoldlng the formatlon of a gel, the alkall-slllcate solutlon and the acld belng slmultaneously fed Into an aqueous alkall-slllcate solutlon whlle for the preclp-ltatlon of the slllca Into an alkall-slllcate solutlon havlng a concentratlon of approxlmately 5 to 25 g of Sl02 per lltre of solutlon the acld and the alkall-slllcate solutlon are so fed wlth sPeclflc solutlon concentratlons and speclflc feed rates whlle malntalnlng a preclpltatlon temperature of between 80 and 90C In the reactlon medlum, the vlscoslty of the reac-tlon medlum Is kept unlformly low durlng a perlod of at least 30X of the total preclpltatlon tlme, the pH value Is kept between 10 and 12 and the addltlon of the reactants Is terml-nated before the vlscoslty, on passlng through a maxlmum, has decreased to a value of less than 100% above the Inltlal vls-coslty, the pH Is adJusted wlth sulphurlc acld to a value below 7 and, secondly an abraslve preclpltated slllca suspen-slon Is produced by a process In whlch an orlglnal preclpl-tated slllca suspenslon whlch Is produced by preclpltatlon ofthe slllca from an alkall-slllcate solutlon havlng a concen-tratlon of approxlmately 5 to 25 g of Sl02 per lltre of solu-tlon wlth an acld alkali metal-slllcate solutlon havlng a spe-clflc solutlon concentratlons and speclflc feed rates whlle malntalnlng a preclpltatlon temperature of between 80 and 90C
In the reactlon medlum, whlle, when requlred, the vessel con-tent Is Intenslvely sheared durlng the entlre preclpltatlon tIme, the vlscoslty of the reactlon medlum Is kept unlformly low durlng a perlod of at least 30% of the entlre preclplta-tlon tlme and the pH val~e Is kept between 10 and 12 and the addltlon of the reactants Is termlnated before the vlscoslty, -' 1 3 ~ 3 on passlng through a maxlmum, has decreased to a value of less than 100% above the Inltlal vlscoslty, the pH IS adJusted wlth sulphurlc acld to a value of 7 to 9, followed by dllutlng wlth hot water to a preclpltated slllca content of 10 to 30 g per lltre and a sodlum sulphate content of 6 to 20 g per lltro and by heatlng to 80 - 90C and whlle keeplng thls pH value con-stant by a slmultaneous feed of alkall metal-slllcate solu-tlon, sulphurlc acld and, when re~ulred, hot water over a pre-clpltatlon tIme of 15 to 180 mlnutes a flnal concentratlon of preclpltated slllca of 40 to 80 g per lltre Is obtalned, whereupon the suspenslon Is acldlfled wlth sulphurlc acld to a pH value of below 7, the two preclpltated slllca susPenslons are mlxed wlth each other and the preclpltatlon slllca Is fll-tered off, wash, spray-drled and then ground wlth an alr-Jet mlll. In a preferred embodlment the thlckenlng slllca suspen-slon Is produced substantlally accordlng to DE-AS 1467019.
The abraslve preclpltated slllca suspenslon Is produced sub-stantlally accordlng to DE-OS 3114493, Example 10.
The present Inventlon also relates to a preclpltated slllca characterlzed by the fo I I ow I ng phys I cal-chemlcal char-acterlstlc data:
loss on drylng (DIN 53198) X 3 - 7 conductIvlty at 25C ~ S 250 - 400 (4X suspenslon) pH value (5% accordlng to DIN 53200) 6 - 7 BET surface area (DIN 66131) sqm/g220 - 250 tamped denslty (DIN 53194) g/lltre80 - 120 macropore volume D ~ 30 nm m I /g3.2-4.0 (accordlng to the Hg pressure method) oll absorptlon accordlng to Gardner ml/lOOg 200 - 220 water retentlon value X 77 - 78 Cu abraslon mg 8 - 1~
RDA abraslon 60 - 80 `~ ~ 3 2 ~ ~';.J '; i REA ~bra~ I on 60 - 90 scratches few vlscoslty mPas 14000-18~00 (In a 16% glycerol-water dlsperslon 1:1, splndle D wlth helIpath) Fe content p.p.m. 70 - 90.
The present Inventlon also relates to a process for produclng the preclpltated slllca whlch has the followln~
physlcal-chemlcal characterlstlc data:
loss on drylng (DIN 53198) % 3 - 7 conductlvlty at 25C ~S 250 - 400 (4% suspenslon) pH value (5% accordlng to DIN 53200) 6 - 7 BET sur~ace area (DIN 66131) sqm/g 220 - 250 tamped denslty (DIN 53194) g/lltre 80 - 120 macropore volume D ~ 30 nm m I /g3.2-4.0 (accordlng to the Hg pressure method) oil absorptlon accordlng to Gardner ml./100g 200 - 220 water retentlon value X 77 - 78 Cu abraslon mg 8 - 12 RDA abraslon 60 - 80 REA abraslon 60 - 90 scratches few vlscoslty mPas 14000-18000 (In a 16% glycerol-water suspenslon 1:1, splndle D wlth helIpath) Fe content p. p.m. 70 - 90.
In the process flrstly an abraslve preclpltated, slllca suspenslon Is produced In that an orlglnal preclpltated slllca suspenslon whlch Is so produced by preclpltatlng the slllca from an alkall-slllcate solutlon havlng a concentratlon of approxlmately 5 to 25 kg of Sl02 per lltre of solutlon wlth an acld and alkall slllcate solutlon havlng speclflc solutlon concentratlons and speclflc feed rates whlle malntalnlng a preclpltatlon temperaturè of between 80 and 90C In the reac-~ ~ 3 ,~, ~
tlon medlum, the vl 9COS I ty of the reactlon medlum Is kept unl-formly low durlng a perlod of at least 30% of the total pre-clpltatlon tlme and the pH value Is kept between 10 and 12 and the addltlon of the reaCtantS IS termlnated before the vlscos-lty, on passlng through a maxlmum, has decreased to a value less than 1oo% above the Inltlal vlscoslty, the pH Is adJusted wlth sulphurlc acld to a value of 7 to 9, followed by dllutlng Wlth hot water to a preclpltated slllca content of 10 to 30 9 per lltre and a sodlum sulphate content of 6 to 20 g of Na2S04 per lltre and by heatIng to 80 - 90C, adJustIng the pH wlth sulphurlc acld to a value of 7 to 9 and whlle keeplng thlS pH
value constant by a slmultaneous feed of alkall metal-slllcate solutlon, sulphurlc acld and, when requlred, hot water over a preclpltatlon tlme of 150 to 180 mlnutes a fInal concentratlon of preclpltated slllca of 40 to 80 g per lltre Is obtalned, whereupon the suspenslon Is acldlfled wlth.sulphurlc acld to a pH value of below 7, and secondly a further preclpltated sll-Ica suspenslon Is produced by a process whlch the preclplta-tlon Is carrled out In a strongly acld pH range, preferably at a pH value of between 1.5 and 2.5 by a conventlonal slmultane-ous addltlon of the sodlum slllcate and acld solutlons to a20 recelver wlth substances dlssolved In water whlch form Iron-soluble complex compounds, the two preclpltated slllca suspen-slons are mlxed wlth each other and the preclpltated slllca Is flltered off, washed, spray-drled and then ground In an alr-Jet mlll. In a preferred embodlment the abraslve preclpltated slllca suspenslon Is produced substantlally accordlng to DE-OS
3114493, Example 10. The further preclpltated slllca suspen-slon Is preferably produced accordlng to DE-PS 1293138, the substances deflned thereln, preferably sodlum fluorlde and oxallc acld, belng used as complexlng agents.
It has now bee~ found that by mlxlng, In the suspen-t C'~
slon phase, preclpltated slllcas havlng varylng propertles partlcularly valuabl e preclpl tated Slll cas for use In dentl-f rlces are obtalned. Sultable preclpltated slllcas are obtalnable dlrectly by preclpltatlng or by resuspendlng the fllter dough of preclpltated slllca. Preclpltated slllca sus-penslons produced dlrectly by preclpltatlon are preferably used.
The preclpltated slllcas obtalned by mlxlng preclpl-tated slllcas In accordance wlth the present Inventlon, I.e., by fl Iterlng, drylng and grlndlng, have more favourable pro-1~ pertles In dentlfrlces than dry mlxtures of the same startlngpreclpltated slllcas In the same ratlo.
The preclpltated slllcas accordlng to the present Inventlon show synerglstlc effects such that wlth glven effect of vlscoslty and thlckenlng there occur an unexpectedly hlgh abraslvlty, I.e., the vlscoslty-abraslvlty relatlon surprls-lngly does not proceed llnearly (see Flg. 1).
The preclpltated slllcas accordlng to the present Inventlon can be produced wlth advantage In a partlcularly easy manner slnce the amounts can be exactly adJusted contlnu-ously or In batches by means of volume or welght measurements at known solld contents. Furthermore, the wet process does not cause any dust problems. Separatlon phenomena are also mlnlmlzed. As compared wlth dry mlxtures the components In wet mlxtures lose part of thelr Identlty. On mlxlng and pre-sumably on drylng In partlcular there result Interactlons, smaller ones of large partlcles, the small partlcles belng added on to larger ones or growlng thereon.
Varlous forms of mutual flocculatlon and penetratlon In the aqueous phase must be taken Into account.
A flrst clear ~Istlnctlon between dry mlxture and wet mlxture Is evldent from the partlcle slze dlstrlbutlon of ~ 3~
the ground samples. Whlle the dry mlxture of two preclpltated slllcas of dlfferent partlcle slze and denslty shows, as expected, two maxlma in the measUrement wlth the Coulter counter and the correspondlng curve has a peak, the curve of the same precipltated slllcas, mlxed wlth each other In the same ratlo whlle wet, follows a completely harmonlc course (see Flg. 2).
A further aPPreclable dlfference lles In the effect of thlcken I ng. The preclpltated slllca accordlng to the pre-sent Inventlon Increases the vlscoslty of a model mlxture of glycerol and water dlstlnctly less than the dry mlxture.
Preclpltated slllcas havlng moderate thlckenlngpower allow hlgher degrees of fllllng and thus the productlon of pastes of "full" character.
As compared therewlth, Pastes fllled to a lower degree have an "empty" and "aqueous" effect In the mouth.
The thlckenlng effect of the preclpltated slllca must fully develop on belng Incorporated Into the toothpaste mass, I.e., thereafter there must be no change In the rheolog-lcal characterlstlc of the toothpaste whlch would render the fllllng and subsequent emptylng of the tubes and contalners dlfflcult or make It even Imposslble.
Fundamentally a dentlfrIce Is supposed to supportand Increase the cleanslng actlon of a tooth brush In that there Is bulld-up between brlstle and tooth surface a fllm that mechanlcally removes layers formed on the teeth.
Thls performance can only be produced by an agent havlng abraslve propertles.
It Is self-evldent that an Identlcal abraslon per-formance preclpltated slllcas produclng the fewest scratches to be preferred.
The preclpltated slllcas accordlng to the present -~ ~ r~ ~ ~
~ ;~) h ~ J l 1 stable vlscoslty development to an average extent wlth hlgh abraslv~ and cleanslng actlon whlle avoldlng deep scratches.
The measurement of the abraslvlty Is carrled out on extracted human teeth rendered radloactlve, I.e., on the exposed dentlne (RDA value) or on the tooth enamel (REA
value). In each case the Increase of the radlo~ctlvlty of the suspenslon of the dentlfrlce to be tested after defIned work-lng on the test teeth wlth brushes Is measured.
As a substltute the decrease In welght of copper plates on brushlng wlth test suspenslon can be determlned.
However, the values thus obtalned can frequently not be com-pared wlth RDA and REA values.
Wlth Improved, I.e., mlcroscoplc methods In speclal laboratorles Informatlon on the cleanslng and pollshlng effect of dentlfrlces Is obtalned and samples causlng many or deep scratches are elImlnated. These tests are carrled out on extracted anImal and human teeth.
An Idea of the slze and number of scratches caused by a dentlfrlce Is obtalned even by mlcroscoplc or stereo-mlcroscoplc examlnatlon of metal plates treated In a defInedmanner llke those obtalned, for example, In the measurement of copper dust.
Apart from thlckenlng propertles and gentle cleans-lng and pollshlng actlon, for health reasons a preclpltated slllca Is today expected to have a hlgh degree of purIty wlth regard to heavy metal contents. Furthermore, hlgher Iron con-tents can result In dlscoloratlons of the pastes, whlch to some extent are coloured and transparent. Thus, a paste coloured blue wlth Indlgotln can have a greenlsh dlscol-oratlon. Furthermore, the aPplIcant has also found that Inthe selectlon of certaln slllcas by means of the wet mlxtures 13~''.1''~1~J'~
very pure products wlth partlcularly low Iron contents are obtalned.
The preSent Inventlon also relates to the use of the preclpltated slllca accordlng to the present Inventlon as abraslve and pollshlng agent In toothpastes.
ExamDl~e The sollds content (preclpltated slllca content) of the preclpltated slllca suspenslon Is determlned as follows:
250 m/ of the preclpltated slllca suspenslon, cooled to 20C, are flltered by suctlon on a porcelaln suctlon fllter (dlam.
120 mm) and the fllter cake Is then washed wlth 500 ml of water untll It Is low In electrolytes. The cake Is drled at 105C to a constant welght.
Computatlon: g welghed out x 4 - g of solIds per lltre.
ExamDle 1 A preclpltated slllca havlng a thlckenlng effect Is substantlally produced accordlng to DE-AS 1467019. In a varl-atlon, for economlc reasons concentrated sodlum slllcate solu-tion denslty ~ , 1.353 g/ml) and concentrated sulphurlc acld (96X) are used for thls PurPose. Thls results In a sollds content of 85 g per lltre In the preclpltated slllca suspenslon.
In a rubber-coated 120-lltre preclpltatlng vessel 73 lltres of hot water and 5.25 lltres of sodlum slllcate solu-tlon (denslty 6 1.353 g~ml, molar ratlo Sl02:Na20 - 3.46) are heated to 85C whlle stlrrlng. Durlng the next 90 mlnutes whlle stlrrlng and malntalning the temperature there are slmultaneously added to thls alkalIne preclpltatlon recelver 16.5 lltres of sodlum slllcate solutlon (denslty ~ ~ 1.353 30 g/ml, molar ratlo S102:N~20 ~ 3.46) wlth 11.0 lltre/hour and 1.448 lltres of sulphurlc acld (96%) wlth 0.965 per ~ 3 ~ ( I .;,; , lltre/hour. The addltlon of the reactants Is termlnated before the vlscoslty of the reactlon medlum, on passlng through medlum, has decreased to a value less than 100% above the Inltlal vlscoslty. The preclpltated slllca suspenslon thus obtalned Is then adJusted wlth sulphurlc acld (96%) to a pH value of 3.5. Thls Is achleved by an Inflow of acld ~t 1.25 lltres/hour exte~dlng oVer several mlnutes. The preclpl-tated slllca suspenslon thus obtalned has a solld content of 85.0 g per lltre.
Examo!e~_~
Thls exampte descrlbes the productlon of an abraslve preclpltated slllca accordlng to DE-OS 31 14 49a, Example 10, bUt wlth the dlfference that the entlre amount of water Is added to the preclpltatlon recelver so that the addltlon of water durlng the preclpItatlon Is omltted and the preclpIta-tlon tlme Is extended from 60 to 100 mlnutes.
In a rubber-coated 120-lltre preclpltatlon vessel 75 lltres of hot water and 5.25 lltres of sodlum slllcate solu-tlon (denslty D 1.353 g/ml; molar ratlo: Sl02:Na20 - 3.46) are heated to 85C whlle stlrrlng. Durlng the subsequent 90 mlnutes whlle stlrrlng and malntalnlng the temperature of 85C
there are added slmultaneously to thls alkallne preclpltatlon recelver 16.5 lltres of sodlum slllcate solutlon (denslty -1.353 g/ml; molar ratlo Sl02:Na20 - 3.46) wlth 11.0 lltres/h and 1.448 lltres of concentrated sulphurlc acld (96%) wlth 0.965 lltre per hour. The addltlon of the reactants Is termlnated before the vlscoslty of the reactlon medlum, on passlng through a maxlmum, has decreased to a value less than 100% above the Inltlal vlscoslty.
The preclpltated slllca suspenslon thus obtalned Is then adJusted wlth sulph~rlc acld (96%) to a pH value of 8.5.
Thls Is achleved by an Inflow of acld at 1.25 lltres per hour --- ~l3~
extendlng over sever~l ml nutes. Th~ preclpltated slllca sus-penslon thUs obtalned has a solld content of 85 g per lltre;
Its Na2S04 content Is 65 g per lltre.
Durlng the entlre preclpltatlon tlme of 90 mlnutes the vessel content Is Intenslvely sheared by a centrlfugal pump clrculatlng the vessel content several tlmes. Detalled data on the equlpment nnd apparatus and on the condltlons of shearlng are evldent from DE-PS 17 67 332, partlcularly from column 8, llnes 31 to 68.
The orlglnal preclpltated slllca suspenslon thus produced Is adJusted wlth water to a preclpltated slllca con-tent of 13 g per lltre and 8.5 g of Na2S04 per lltre.
16.06 lltres of thls suspenslon are heated to 85CIn a rubber-coated 120-lltre preclpltatlon vessel whlle stlr-rlng. Whlle malntalnlng thls temperature and a pH value of 8.5 there are slmultaneously added to the preclpltated slllca suspenslon durIng a perlod of 100 mlnutes 23.1 lltres of sodlum slllcate solutlon (denslty ~ ~ 1.33 g/ml; molar ratlo Sl02:Na20 3.46) at a rate of 231.0 m/ per mlnute and 1.94 lltres of sulphurlc acld (96%) at a rate of 19.4 ml per mlnute. The preclpltated slllca suspenslon Is subsequently adJusted wlth sulphurlc acld (96%) to a pH value of approxl-mately 3.5. The preclpltated slllca suspenslon has a solld content of 92.0 g per lltre. The preclpltated slllca obtalned on fllterlng off and washlng has the physlcal-chemlcal charac-terlstlc data complled In Table 1.
ExamDle 3 18.5 cu m of the suspenslon of the abraslve preclpl-tated slllca suspenslon havlng a preclpltated slllca content of 92.0 g per lltre accordlng to Example 2 are mlxed wlth 40.0 30 cu m of thlckenlng precl~ltated slllca accordlng to Example 1 havlng a content of preclpltated slllca of 85.0 g per lltre correspondlng to a welght ratlo of 1:2 - (relatlve to the pre-clpltated slllca content).
For the further treatment the preclpltated slllca of thls suspenslon mlxture Is separated by means of fllter presses. The preclpltated slllca content In the fllter press dough Is 24%. The washed and spray-drled fllter press Is ground In an alr-Jet mlll. The preclpltated slllca thus obtalned has the physlcal-chemlcal characterlstlc data com-plled ~n Table 1.
ExamDle 4 1.0 kg of the washed, drled and ground thlckened preclpltated slllca of Example 1 Is mlxed, whlle dry, wlth the abraslve preclpltated slllca of Example 2 that also has been washed, drled and ground In a comParable manner, I.e., the welght ratlo of the two preclpltated slllcas Is 1:2 as In Example 3.
The preclpltated slllca obtalned has the physlcal-chemlcal characterlstlc data complled In Table 1.
ExamDle 5 As deflned In DE-OS 31 14 493.4, Example 12 an abra-slve preclpltated slllca Is flrst produced as follows: In a preclpltatlon vessel fItted wlth a stlrrer 27.0 cu m of water and 10.0 cu m of preclpltated slllca suspenslon substantlally as In DE-AS 14 67 019, whlch Is acldtfled only to pH 8.5 and has a slllca content of 8.5 g per lltre, are mlxed and heated to 85C. Dlfferlng from DE-AS 14 67 019, concentrated sodlum slllcate solutlon (denslty 1.353 g/ml) and concentrated sul-phùrlc acld (96X) are applled for economlc reasons, resultlng In a content of sollds of 85 g per lltre In the preclpltated slllca suspenslon. At thls temperature and whlle malntalnlng a pH value of 8.5 to 9 t~here are slmultaneously added for a perlod of 80 mlnutes 9.6 cu m of sodlum slllcate solutlon ~ 3 ,~ ~ ;J ~
(denslty ~ 1.353 g/ml modulus Sl02:Na20 - 3.46), 0.94 cU m of concentrated sulphurlc acld (96X) and 20.0 cu m of hot water.
On completed preclpltatlon the pH of the suspenslon Is adJusted to a value of 3.5, usln3 concentrated sulphurlc acld (96X). The content of preclpltated slllca Is 66.0 g per lltre.
25 . 75 CU m of thls preclpltated slllca suspenslon are mlxed wlth 40.0 cu m of the suspenslon of a thlckenlng slllca content of 85.0 g per lltre correspondlng to a welght ratlo of 1:2 (relatlve to the solld content).
For the further treatment the procedure Is llke that In Example 1. The slllca content In the fllter press dough Is 21X.
The preclpltated slllca obtalned has the physlcal-chemlcal characterlstlc data complled In Table 1.
Examole ~
A preclpltated slllca low In Iron content Is pro-duced accordlng to Example 1 of D 47 633 (- DE-PS 12 93 !38)-18.5 lltres of water are put Into a cyllndrlcal, 30-lltre wooden tank provlded wlth a wooden blade mlxer (dlameter20 cm, helght 6 cm, 90 r.p.m.).
The water Is Indlrectly heated to 85C wlth an acld-proof steam-coll. In the recelver 25 g of sodlum fluorlde and 6.25 g of oxallc acld are dlssolved.
Whlle stlrrlng and malntalnlng a pH value of 2.0 5.45 lltres of a commerclal sodlum slllcate (molar ratlo of Na20:SlO2 1:3.36, denslty ~ - ,1.34) and 0.65 lltre of sul-phurlc acld 96% of H2SO4) were fed In wlthln 90 mlnutes at opposlte polnts.
Stlrrlng of the nascent suspenslon Is contlnued for approxlmately 30 mlnutes, followed by flIterlng on suctlon fllters In a conventlonal manner, uslng twlce the amount of 3 ~ ~ . ' t ~ .
water, relatlve to the volume of the suspenslon, wh I ch I S then washed, spray-drled and ground wlth an alr-Jet mlll.
Examcle 7 18.3 cu m of susPenslon of the abraslve slllca accordlng to Example 2 havlng a preclpltated slllca content of 92.0 g per lltre are then mlxed wlth 40.0 cu m of suspenslon of a preclpltated slllca low In Iron accordlng to Example 1 of D 47633 ~_ DE-PS 12 93 138) havlng a preclpltated slllca con-tent of 83.8 9 per lltre correspondlng to a welght ratlo of 1:2.
For the further treatment the procedure Is llke that In Example 3. The slllca content In the press dough Is 23%. -The preclpltated slllca obtalned has the physlcal-chemlcal characterlstlc data complled In Table 1.
ExamDle 8 For the productlon of a preclpltated slllca that Is low In Iron and has thlckenlng and cleanslng propertles the suspenslon of a low-lron content slllca produced accordlng to Example 1 of DE-PS 12 93 138 (- D 4763~3) Is mlxed In speclflc ratlos wlth the suspenslon of the abraslve slllca produced accordlng to Example 2. Table 2 shows that any welght ratlo the Iron content of the mlxture Is lower than that of the com-parable dry mlxture.
Table 2 Mlxture Ratlos In Parts by Welaht abraslve slllca as descrIbed 2 slllca low In Iron accordlng to Example 1 of D 47633 1 1 2 . _ 30wet mlxture ~ 157 p.p.m. 118 p.p.m. 80 p.p.m.
Fe Fe F~
1 3 ~
dry mlxture 168 p.p.m. 137 p.p.m. 101 p.p.m.
Fe Fe Fe ~ ~ o,~ c v;, ~ o FJ-- --n 1-ta ~ o o ~3 n u~ t~ ,p ~ ~
n 5'~ ~ e: Q ~ ' ~ ~
c ~ ~ n o l ~o tO1~ 0 ~ 1;
O dP ~ U) U~ r~ 1l_ ~a P O~ p p ~a ~ p ~ D p 0 P) n t~
~ 0 ~ ;1H ^ I Ul H
~ 0 ~
(D --t ~
3 n~ 3 ~ ~ 3 (o 3 W
n U~ O IC~ ~ O
1~1 tq N N ~ N W `0~ ~I 3 - O~ o~: N N Oo oo ~ 00 C0 ~ W ~ n .
O O ~ Ul W --~ O O , 00 0 ~11 W O ~D
W
~p, ~ o~ ~ x ~ O ~ W ~) N Ul Oo ~ 0~ ~ n 3 O O '~O O O O~ o ~ O O ~o O 'U .
` ` w ` ~ ~ ~
N O H. ~ oo ~ ~ oo ~ W ~ ~ ~ ~n X
rv o~ ~ o o o w o ~a ~D-.
w N ~ ~ O ~ I ~ ~ N ~ ~ n X
O O ,~ O O W r~ O u~ ~ O ~ n .3 ~ .
Xq N Ul ,~ ` W ~ ~ 0~ 0~ 3 ~ $ 1 Hl ~ ,~W~ o Oo O 00 W O r~
u~
~ W W W O~ N tq W 0 ~ N CO 0 ~ n ~3a ~n o o u~ ~ ~ o ~,n o o ~ o ~--$ ~ ID
3 0 a~
~ ~ N Xq ~D --I ~0 O ~ O W ~ ~O r A ~3a o o ~ n o ~ ~ o oo o ~ ~ n O I_ ~ I
1 3 w ~
The physl CA l-chemlcal characterlstlc data deflned In the present applIcatlon Are determlned as follows:
Loss on Drylng accordlng to DIN 53198.
Conductlvlty at 25C/4% suspenslon.
A sample of 4.0 g Is heated wlth 60 m/ of completoly fully desalted water In a 150 m/ beaker and bolled for one mlnute whlle stlrrlng. The suspenslon Is then transferred Into a 100 m/ flask, cooled and fllled up to the mark wlth completely full desalted water. The electrlc conductlvlty Is measured wlth a commerclal measurlng devlce, for example, of the "WlssenschaftlIche Werkstatten (WTW), conductlmeter type LF530, at 25C.
pH Value In a 6% dlsperslon accordlng to DIN 63200.
BET Surface Area accordlng to DIN 66131.
A sample Is rlnsed wlth nltrogen at 100C. The vol-umetrlc measurement Is carrled out wlth pure nltrogen at the temperature of the llquld nltrogen (-195.8C).
Tamped Denslty accordlng to DIN 53194.
The test Is carrled out wlthout pretreatlng the sample.
Macropore Volume D ~ 30 nm accordlng to ~he Hg pres-sure method.
The measurement Is carrled out wlth the Mercury Pressure Poroslmeter, 200 Serles of the flrm of Carlo Erba Strumentazlone.
OiI Absorptlon accordlng to Gardner-Coleman accord-lng to ASTM:D 1483-~0.
Water Retente Value.
The water retentlon value Indlcates the portlon of water contalned In the press dough upon squeezlng out preclpl-tated slllca suspenslon and washlng to a pauclty of elec-trolyte. For the computatlon 250 g of press dough are drled ~ 3 2 ..; ,. i i at 105C untll a constant welght Is attalned.
Computatlon - wel,ahed out X 100 100 - - X water retentlon value welghed sample.
Partlcle Slze Dlstrlbutlon accordlng to Coulter Counter/100~ caplllary.
The measurement Is carrled out wlth the Coulter Counter model TA I I of the flrm of Coulter Electronlcs GmbH.
Determlnatlon of the Cu Abraslon In a 10% Glycerol Dlsperslon:
a) Productlon of the alycerol Dlsperslon 153 g of glycerol (anhydrolcs, purest Ph Eur, BP USP, denslty 1.26 g~m/, fIrm of Merck, Darmstadt) are welghed Into a polyethylene beaker (250 m/). 17 g of preclpltated slllca are carefully Inter-mlxed wlth a spatula. The mlxture Is subsequently homogenlzed for 12 mlnutes wlth a blade agltator (dlameter 5.2 cm) at 1500 r . p . m .
b) Abraslon Measurlng Procedure The determlnatlon of the abraslon measurement Is carrled out In an abraslon testlng devlce, whlch Is known from followlng Publlcatlons (1) Pfungle: Fette, Selfen, Anstrlchmlttel, 63 (5) (1961), Page 445 to 4B1. "Abraslon und Relmgunskraft von Putz Korpern In Zahnpasten" (2) A. Reng, F. Danny; Parfumerle und Kosmetlk 59 (2) (197S), Page 37 to 45; "Anwendungstechmlsche Prufung von Zahnpasten". For thls purpose each of the slx troughs of the testIng devlce Is coated wlth 20 m/ of the homogeneous dlsperslon. The abraslon caused by slx surface-ground nylon brushes on slx surface-30 ~round Cu sheets (electrolyte-copper) In fIve hours wlth 50000 up and down strokes Is determlned by dlfferentlal welghlng.
When comPutlng the abraslvlty average values are formed from 1 ~ 2; ' `
the values obtalned. The abraslon (abraslvlty) Is deflned In mg of Cu.
RDA Abr~s I on .
The method Is descrlbed In Journal of Dental Research, 56(4), 663 (1976) and Is also applled to the REA
abraslon test.
REA Abras I on .
Scratches are determlned vlsually by means of a mlcroscope.
Determlnatlon of the Vlscoslty measured In a 16%
glycerol-water dlsperslon (mlxture 1:1) wlth a Brookfleld Vls-coslmeter RTV, splndle 10, wlth helIpath at 10 r.p.m.1. Test Mlxtures 48 g of slllca 126 g of glycerol (approxlmately 87%, purest Ph Eur. BP, den-slty ~ 1.26 g~m/ flrm of Merck, Darmstadt) 126 g of dlstllled water 300 g of a 16X dlsperslon, relatlve to slllca.
2. Procedure.
In a 400 m/ beaker glass (broad shape) the abraslve slllcas are stlrred by hand Into the glycerol-water mlxture wlth a glass rod (1 mlnute) and allowed to stand for Z4 hours. The vlscoslty Is measured thereafter.
3. Measurement.
The measurement of the vlscoslty Is carrled out In the same - ~ ~ dte~7a~k beaker wlth a Brookfleld-vlscoslmeter~ RVT, spindle 10 wlth helIpath at 10 r.p.m.
The present Inventlon relates to preclpltated slll-cas, a process for thelr productlon and to thelr use In tooth pastes.
Syn~hetlcally produced preclpltated slllcas havo been of great Importance as a component of dentlfrlces for many years. They are very pUre, toxlcologlcally unobJectlon-able and compatlble wlth the other substances contalned In tooth pastes, as for example, glycerol, sorbltol, thlckeners, detergents, dyes and aromatlc substances and, when requlred, soluble fluorlne compounds.
Synthetlc preclpltated slllcas are produced by pre-clpltatlon from alkall-slllcate solutlons wlth aclds In a stlrrlng process, by fllterlng the suspenslon off, washlng, drylng and grlndlng. The preclpltatlon process provldes the posslblllty of readlly predetermlnlng Important propertles, such as partlcle dlameter, partlcle shape and partlcle denslty or hardness by operatlons In the flocculate phase.
The present Inventlon provldes a process for the productlon of cleanlng, pollshlng and thlckenlng preclpltated slllcas for dentlfrlces In whlch the slllcas of varylng partl-cle slze and partlcle denslty obtalned In the current manner by preclpltatlon are homogeneously mlxed wlth each other In the suspenslon phase and the mlxtures are further treated In a conventlonal manner by fllterlng, washlng, drylng and grlndlng.
The present Inventlon also provldes a preclpltated slllca whlch Is characterlzed by the followlng physlcal-cheml-cal characterlstlc data:
loss on drylng (DIN 53198) X 3 - 7-conductlvlty at 25C
(4% suspenslon) ~ S 400 - 800 pH vzlue (5X accordlng to DIN 53200) 6 - 7 `` ~ 3 h ~ 2 ~L, BET surface area (DIN 66131) sqm/g 130 - 150 tamped denslty (DIN 53194) g/lItre 100 - 150 macropore volume D ~ 30 nm ml/g 3.2-4.0 (~ccordln~ to the H~ pr~sur~ mcthod) oll absorptlon accordlng to Gardner ml/100 9 180 - 200 water retentlon value X 76 - 79 Cu abraslon mg 5 - 14 RDA abraslon 35 - 100 REA abraslon 40 - 90 scratches few to very few vlscoslty mPas 5000-10000 (In a 16X glycerol-water dlsperslon 1:1, splndle D wlth hellpath) Fe content p.p.m. 240-280.
The present Inventlon also provldes a process for produclng the preclpltated slllca whlch Is characterlzed by the followlng physlcal-chemlcal characterlstlc data:
loss on drylng (DIN 53198) % 3 - 7 conductlvlty at 25C ~ S 400 - 800 (4X suspenslon) pH value (5% accordlng to DIN 53200) 6 - 7 BET surface area (DIN 66131) sqm/g130 - 150 tamped denslty (DIN 53194) g/lItre100 - 150 macropore volume D , 30 nm ml/g 3.2-4.0 (accordlng to the Hg pressure method) oll absorptlon accordlng to Gardner ml/lOOg 180 - 200 water retentlon value % 76 - 79 Cu abraslon mg 5 - 14 RDA abraslon 35 - 100 REA abraslon 40 - 90 scratches few to very few vlscoslty ~ mPas 5000-10000 (In a 16% glycerol-water dlsperslon 1:1, splndle D wlth helIpath) Fe contcnt p.p.m. 240 - 280 In whlch process flrstly a thlckenlng preclpltated slllca sU
penslon IS produced by reactlng an alkall-slllcate solutlon wlth an acld whlle avoldlng the formatlon of a gel, the alkall-slllcate solutlon and the acld belng slmultaneously fed Into an aqueous alkall-slllcate solutlon whlle for the preclp-ltatlon of the slllca Into an alkall-slllcate solutlon havlng a concentratlon of approxlmately 5 to 25 g of Sl02 per lltre of solutlon the acld and the alkall-slllcate solutlon are so fed wlth sPeclflc solutlon concentratlons and speclflc feed rates whlle malntalnlng a preclpltatlon temperature of between 80 and 90C In the reactlon medlum, the vlscoslty of the reac-tlon medlum Is kept unlformly low durlng a perlod of at least 30X of the total preclpltatlon tlme, the pH value Is kept between 10 and 12 and the addltlon of the reactants Is terml-nated before the vlscoslty, on passlng through a maxlmum, has decreased to a value of less than 100% above the Inltlal vls-coslty, the pH Is adJusted wlth sulphurlc acld to a value below 7 and, secondly an abraslve preclpltated slllca suspen-slon Is produced by a process In whlch an orlglnal preclpl-tated slllca suspenslon whlch Is produced by preclpltatlon ofthe slllca from an alkall-slllcate solutlon havlng a concen-tratlon of approxlmately 5 to 25 g of Sl02 per lltre of solu-tlon wlth an acld alkali metal-slllcate solutlon havlng a spe-clflc solutlon concentratlons and speclflc feed rates whlle malntalnlng a preclpltatlon temperature of between 80 and 90C
In the reactlon medlum, whlle, when requlred, the vessel con-tent Is Intenslvely sheared durlng the entlre preclpltatlon tIme, the vlscoslty of the reactlon medlum Is kept unlformly low durlng a perlod of at least 30% of the entlre preclplta-tlon tlme and the pH val~e Is kept between 10 and 12 and the addltlon of the reactants Is termlnated before the vlscoslty, -' 1 3 ~ 3 on passlng through a maxlmum, has decreased to a value of less than 100% above the Inltlal vlscoslty, the pH IS adJusted wlth sulphurlc acld to a value of 7 to 9, followed by dllutlng wlth hot water to a preclpltated slllca content of 10 to 30 g per lltre and a sodlum sulphate content of 6 to 20 g per lltro and by heatlng to 80 - 90C and whlle keeplng thls pH value con-stant by a slmultaneous feed of alkall metal-slllcate solu-tlon, sulphurlc acld and, when re~ulred, hot water over a pre-clpltatlon tIme of 15 to 180 mlnutes a flnal concentratlon of preclpltated slllca of 40 to 80 g per lltre Is obtalned, whereupon the suspenslon Is acldlfled wlth sulphurlc acld to a pH value of below 7, the two preclpltated slllca susPenslons are mlxed wlth each other and the preclpltatlon slllca Is fll-tered off, wash, spray-drled and then ground wlth an alr-Jet mlll. In a preferred embodlment the thlckenlng slllca suspen-slon Is produced substantlally accordlng to DE-AS 1467019.
The abraslve preclpltated slllca suspenslon Is produced sub-stantlally accordlng to DE-OS 3114493, Example 10.
The present Inventlon also relates to a preclpltated slllca characterlzed by the fo I I ow I ng phys I cal-chemlcal char-acterlstlc data:
loss on drylng (DIN 53198) X 3 - 7 conductIvlty at 25C ~ S 250 - 400 (4X suspenslon) pH value (5% accordlng to DIN 53200) 6 - 7 BET surface area (DIN 66131) sqm/g220 - 250 tamped denslty (DIN 53194) g/lltre80 - 120 macropore volume D ~ 30 nm m I /g3.2-4.0 (accordlng to the Hg pressure method) oll absorptlon accordlng to Gardner ml/lOOg 200 - 220 water retentlon value X 77 - 78 Cu abraslon mg 8 - 1~
RDA abraslon 60 - 80 `~ ~ 3 2 ~ ~';.J '; i REA ~bra~ I on 60 - 90 scratches few vlscoslty mPas 14000-18~00 (In a 16% glycerol-water dlsperslon 1:1, splndle D wlth helIpath) Fe content p.p.m. 70 - 90.
The present Inventlon also relates to a process for produclng the preclpltated slllca whlch has the followln~
physlcal-chemlcal characterlstlc data:
loss on drylng (DIN 53198) % 3 - 7 conductlvlty at 25C ~S 250 - 400 (4% suspenslon) pH value (5% accordlng to DIN 53200) 6 - 7 BET sur~ace area (DIN 66131) sqm/g 220 - 250 tamped denslty (DIN 53194) g/lltre 80 - 120 macropore volume D ~ 30 nm m I /g3.2-4.0 (accordlng to the Hg pressure method) oil absorptlon accordlng to Gardner ml./100g 200 - 220 water retentlon value X 77 - 78 Cu abraslon mg 8 - 12 RDA abraslon 60 - 80 REA abraslon 60 - 90 scratches few vlscoslty mPas 14000-18000 (In a 16% glycerol-water suspenslon 1:1, splndle D wlth helIpath) Fe content p. p.m. 70 - 90.
In the process flrstly an abraslve preclpltated, slllca suspenslon Is produced In that an orlglnal preclpltated slllca suspenslon whlch Is so produced by preclpltatlng the slllca from an alkall-slllcate solutlon havlng a concentratlon of approxlmately 5 to 25 kg of Sl02 per lltre of solutlon wlth an acld and alkall slllcate solutlon havlng speclflc solutlon concentratlons and speclflc feed rates whlle malntalnlng a preclpltatlon temperaturè of between 80 and 90C In the reac-~ ~ 3 ,~, ~
tlon medlum, the vl 9COS I ty of the reactlon medlum Is kept unl-formly low durlng a perlod of at least 30% of the total pre-clpltatlon tlme and the pH value Is kept between 10 and 12 and the addltlon of the reaCtantS IS termlnated before the vlscos-lty, on passlng through a maxlmum, has decreased to a value less than 1oo% above the Inltlal vlscoslty, the pH Is adJusted wlth sulphurlc acld to a value of 7 to 9, followed by dllutlng Wlth hot water to a preclpltated slllca content of 10 to 30 9 per lltre and a sodlum sulphate content of 6 to 20 g of Na2S04 per lltre and by heatIng to 80 - 90C, adJustIng the pH wlth sulphurlc acld to a value of 7 to 9 and whlle keeplng thlS pH
value constant by a slmultaneous feed of alkall metal-slllcate solutlon, sulphurlc acld and, when requlred, hot water over a preclpltatlon tlme of 150 to 180 mlnutes a fInal concentratlon of preclpltated slllca of 40 to 80 g per lltre Is obtalned, whereupon the suspenslon Is acldlfled wlth.sulphurlc acld to a pH value of below 7, and secondly a further preclpltated sll-Ica suspenslon Is produced by a process whlch the preclplta-tlon Is carrled out In a strongly acld pH range, preferably at a pH value of between 1.5 and 2.5 by a conventlonal slmultane-ous addltlon of the sodlum slllcate and acld solutlons to a20 recelver wlth substances dlssolved In water whlch form Iron-soluble complex compounds, the two preclpltated slllca suspen-slons are mlxed wlth each other and the preclpltated slllca Is flltered off, washed, spray-drled and then ground In an alr-Jet mlll. In a preferred embodlment the abraslve preclpltated slllca suspenslon Is produced substantlally accordlng to DE-OS
3114493, Example 10. The further preclpltated slllca suspen-slon Is preferably produced accordlng to DE-PS 1293138, the substances deflned thereln, preferably sodlum fluorlde and oxallc acld, belng used as complexlng agents.
It has now bee~ found that by mlxlng, In the suspen-t C'~
slon phase, preclpltated slllcas havlng varylng propertles partlcularly valuabl e preclpl tated Slll cas for use In dentl-f rlces are obtalned. Sultable preclpltated slllcas are obtalnable dlrectly by preclpltatlng or by resuspendlng the fllter dough of preclpltated slllca. Preclpltated slllca sus-penslons produced dlrectly by preclpltatlon are preferably used.
The preclpltated slllcas obtalned by mlxlng preclpl-tated slllcas In accordance wlth the present Inventlon, I.e., by fl Iterlng, drylng and grlndlng, have more favourable pro-1~ pertles In dentlfrlces than dry mlxtures of the same startlngpreclpltated slllcas In the same ratlo.
The preclpltated slllcas accordlng to the present Inventlon show synerglstlc effects such that wlth glven effect of vlscoslty and thlckenlng there occur an unexpectedly hlgh abraslvlty, I.e., the vlscoslty-abraslvlty relatlon surprls-lngly does not proceed llnearly (see Flg. 1).
The preclpltated slllcas accordlng to the present Inventlon can be produced wlth advantage In a partlcularly easy manner slnce the amounts can be exactly adJusted contlnu-ously or In batches by means of volume or welght measurements at known solld contents. Furthermore, the wet process does not cause any dust problems. Separatlon phenomena are also mlnlmlzed. As compared wlth dry mlxtures the components In wet mlxtures lose part of thelr Identlty. On mlxlng and pre-sumably on drylng In partlcular there result Interactlons, smaller ones of large partlcles, the small partlcles belng added on to larger ones or growlng thereon.
Varlous forms of mutual flocculatlon and penetratlon In the aqueous phase must be taken Into account.
A flrst clear ~Istlnctlon between dry mlxture and wet mlxture Is evldent from the partlcle slze dlstrlbutlon of ~ 3~
the ground samples. Whlle the dry mlxture of two preclpltated slllcas of dlfferent partlcle slze and denslty shows, as expected, two maxlma in the measUrement wlth the Coulter counter and the correspondlng curve has a peak, the curve of the same precipltated slllcas, mlxed wlth each other In the same ratlo whlle wet, follows a completely harmonlc course (see Flg. 2).
A further aPPreclable dlfference lles In the effect of thlcken I ng. The preclpltated slllca accordlng to the pre-sent Inventlon Increases the vlscoslty of a model mlxture of glycerol and water dlstlnctly less than the dry mlxture.
Preclpltated slllcas havlng moderate thlckenlngpower allow hlgher degrees of fllllng and thus the productlon of pastes of "full" character.
As compared therewlth, Pastes fllled to a lower degree have an "empty" and "aqueous" effect In the mouth.
The thlckenlng effect of the preclpltated slllca must fully develop on belng Incorporated Into the toothpaste mass, I.e., thereafter there must be no change In the rheolog-lcal characterlstlc of the toothpaste whlch would render the fllllng and subsequent emptylng of the tubes and contalners dlfflcult or make It even Imposslble.
Fundamentally a dentlfrIce Is supposed to supportand Increase the cleanslng actlon of a tooth brush In that there Is bulld-up between brlstle and tooth surface a fllm that mechanlcally removes layers formed on the teeth.
Thls performance can only be produced by an agent havlng abraslve propertles.
It Is self-evldent that an Identlcal abraslon per-formance preclpltated slllcas produclng the fewest scratches to be preferred.
The preclpltated slllcas accordlng to the present -~ ~ r~ ~ ~
~ ;~) h ~ J l 1 stable vlscoslty development to an average extent wlth hlgh abraslv~ and cleanslng actlon whlle avoldlng deep scratches.
The measurement of the abraslvlty Is carrled out on extracted human teeth rendered radloactlve, I.e., on the exposed dentlne (RDA value) or on the tooth enamel (REA
value). In each case the Increase of the radlo~ctlvlty of the suspenslon of the dentlfrlce to be tested after defIned work-lng on the test teeth wlth brushes Is measured.
As a substltute the decrease In welght of copper plates on brushlng wlth test suspenslon can be determlned.
However, the values thus obtalned can frequently not be com-pared wlth RDA and REA values.
Wlth Improved, I.e., mlcroscoplc methods In speclal laboratorles Informatlon on the cleanslng and pollshlng effect of dentlfrlces Is obtalned and samples causlng many or deep scratches are elImlnated. These tests are carrled out on extracted anImal and human teeth.
An Idea of the slze and number of scratches caused by a dentlfrlce Is obtalned even by mlcroscoplc or stereo-mlcroscoplc examlnatlon of metal plates treated In a defInedmanner llke those obtalned, for example, In the measurement of copper dust.
Apart from thlckenlng propertles and gentle cleans-lng and pollshlng actlon, for health reasons a preclpltated slllca Is today expected to have a hlgh degree of purIty wlth regard to heavy metal contents. Furthermore, hlgher Iron con-tents can result In dlscoloratlons of the pastes, whlch to some extent are coloured and transparent. Thus, a paste coloured blue wlth Indlgotln can have a greenlsh dlscol-oratlon. Furthermore, the aPplIcant has also found that Inthe selectlon of certaln slllcas by means of the wet mlxtures 13~''.1''~1~J'~
very pure products wlth partlcularly low Iron contents are obtalned.
The preSent Inventlon also relates to the use of the preclpltated slllca accordlng to the present Inventlon as abraslve and pollshlng agent In toothpastes.
ExamDl~e The sollds content (preclpltated slllca content) of the preclpltated slllca suspenslon Is determlned as follows:
250 m/ of the preclpltated slllca suspenslon, cooled to 20C, are flltered by suctlon on a porcelaln suctlon fllter (dlam.
120 mm) and the fllter cake Is then washed wlth 500 ml of water untll It Is low In electrolytes. The cake Is drled at 105C to a constant welght.
Computatlon: g welghed out x 4 - g of solIds per lltre.
ExamDle 1 A preclpltated slllca havlng a thlckenlng effect Is substantlally produced accordlng to DE-AS 1467019. In a varl-atlon, for economlc reasons concentrated sodlum slllcate solu-tion denslty ~ , 1.353 g/ml) and concentrated sulphurlc acld (96X) are used for thls PurPose. Thls results In a sollds content of 85 g per lltre In the preclpltated slllca suspenslon.
In a rubber-coated 120-lltre preclpltatlng vessel 73 lltres of hot water and 5.25 lltres of sodlum slllcate solu-tlon (denslty 6 1.353 g~ml, molar ratlo Sl02:Na20 - 3.46) are heated to 85C whlle stlrrlng. Durlng the next 90 mlnutes whlle stlrrlng and malntalning the temperature there are slmultaneously added to thls alkalIne preclpltatlon recelver 16.5 lltres of sodlum slllcate solutlon (denslty ~ ~ 1.353 30 g/ml, molar ratlo S102:N~20 ~ 3.46) wlth 11.0 lltre/hour and 1.448 lltres of sulphurlc acld (96%) wlth 0.965 per ~ 3 ~ ( I .;,; , lltre/hour. The addltlon of the reactants Is termlnated before the vlscoslty of the reactlon medlum, on passlng through medlum, has decreased to a value less than 100% above the Inltlal vlscoslty. The preclpltated slllca suspenslon thus obtalned Is then adJusted wlth sulphurlc acld (96%) to a pH value of 3.5. Thls Is achleved by an Inflow of acld ~t 1.25 lltres/hour exte~dlng oVer several mlnutes. The preclpl-tated slllca suspenslon thus obtalned has a solld content of 85.0 g per lltre.
Examo!e~_~
Thls exampte descrlbes the productlon of an abraslve preclpltated slllca accordlng to DE-OS 31 14 49a, Example 10, bUt wlth the dlfference that the entlre amount of water Is added to the preclpltatlon recelver so that the addltlon of water durlng the preclpItatlon Is omltted and the preclpIta-tlon tlme Is extended from 60 to 100 mlnutes.
In a rubber-coated 120-lltre preclpltatlon vessel 75 lltres of hot water and 5.25 lltres of sodlum slllcate solu-tlon (denslty D 1.353 g/ml; molar ratlo: Sl02:Na20 - 3.46) are heated to 85C whlle stlrrlng. Durlng the subsequent 90 mlnutes whlle stlrrlng and malntalnlng the temperature of 85C
there are added slmultaneously to thls alkallne preclpltatlon recelver 16.5 lltres of sodlum slllcate solutlon (denslty -1.353 g/ml; molar ratlo Sl02:Na20 - 3.46) wlth 11.0 lltres/h and 1.448 lltres of concentrated sulphurlc acld (96%) wlth 0.965 lltre per hour. The addltlon of the reactants Is termlnated before the vlscoslty of the reactlon medlum, on passlng through a maxlmum, has decreased to a value less than 100% above the Inltlal vlscoslty.
The preclpltated slllca suspenslon thus obtalned Is then adJusted wlth sulph~rlc acld (96%) to a pH value of 8.5.
Thls Is achleved by an Inflow of acld at 1.25 lltres per hour --- ~l3~
extendlng over sever~l ml nutes. Th~ preclpltated slllca sus-penslon thUs obtalned has a solld content of 85 g per lltre;
Its Na2S04 content Is 65 g per lltre.
Durlng the entlre preclpltatlon tlme of 90 mlnutes the vessel content Is Intenslvely sheared by a centrlfugal pump clrculatlng the vessel content several tlmes. Detalled data on the equlpment nnd apparatus and on the condltlons of shearlng are evldent from DE-PS 17 67 332, partlcularly from column 8, llnes 31 to 68.
The orlglnal preclpltated slllca suspenslon thus produced Is adJusted wlth water to a preclpltated slllca con-tent of 13 g per lltre and 8.5 g of Na2S04 per lltre.
16.06 lltres of thls suspenslon are heated to 85CIn a rubber-coated 120-lltre preclpltatlon vessel whlle stlr-rlng. Whlle malntalnlng thls temperature and a pH value of 8.5 there are slmultaneously added to the preclpltated slllca suspenslon durIng a perlod of 100 mlnutes 23.1 lltres of sodlum slllcate solutlon (denslty ~ ~ 1.33 g/ml; molar ratlo Sl02:Na20 3.46) at a rate of 231.0 m/ per mlnute and 1.94 lltres of sulphurlc acld (96%) at a rate of 19.4 ml per mlnute. The preclpltated slllca suspenslon Is subsequently adJusted wlth sulphurlc acld (96%) to a pH value of approxl-mately 3.5. The preclpltated slllca suspenslon has a solld content of 92.0 g per lltre. The preclpltated slllca obtalned on fllterlng off and washlng has the physlcal-chemlcal charac-terlstlc data complled In Table 1.
ExamDle 3 18.5 cu m of the suspenslon of the abraslve preclpl-tated slllca suspenslon havlng a preclpltated slllca content of 92.0 g per lltre accordlng to Example 2 are mlxed wlth 40.0 30 cu m of thlckenlng precl~ltated slllca accordlng to Example 1 havlng a content of preclpltated slllca of 85.0 g per lltre correspondlng to a welght ratlo of 1:2 - (relatlve to the pre-clpltated slllca content).
For the further treatment the preclpltated slllca of thls suspenslon mlxture Is separated by means of fllter presses. The preclpltated slllca content In the fllter press dough Is 24%. The washed and spray-drled fllter press Is ground In an alr-Jet mlll. The preclpltated slllca thus obtalned has the physlcal-chemlcal characterlstlc data com-plled ~n Table 1.
ExamDle 4 1.0 kg of the washed, drled and ground thlckened preclpltated slllca of Example 1 Is mlxed, whlle dry, wlth the abraslve preclpltated slllca of Example 2 that also has been washed, drled and ground In a comParable manner, I.e., the welght ratlo of the two preclpltated slllcas Is 1:2 as In Example 3.
The preclpltated slllca obtalned has the physlcal-chemlcal characterlstlc data complled In Table 1.
ExamDle 5 As deflned In DE-OS 31 14 493.4, Example 12 an abra-slve preclpltated slllca Is flrst produced as follows: In a preclpltatlon vessel fItted wlth a stlrrer 27.0 cu m of water and 10.0 cu m of preclpltated slllca suspenslon substantlally as In DE-AS 14 67 019, whlch Is acldtfled only to pH 8.5 and has a slllca content of 8.5 g per lltre, are mlxed and heated to 85C. Dlfferlng from DE-AS 14 67 019, concentrated sodlum slllcate solutlon (denslty 1.353 g/ml) and concentrated sul-phùrlc acld (96X) are applled for economlc reasons, resultlng In a content of sollds of 85 g per lltre In the preclpltated slllca suspenslon. At thls temperature and whlle malntalnlng a pH value of 8.5 to 9 t~here are slmultaneously added for a perlod of 80 mlnutes 9.6 cu m of sodlum slllcate solutlon ~ 3 ,~ ~ ;J ~
(denslty ~ 1.353 g/ml modulus Sl02:Na20 - 3.46), 0.94 cU m of concentrated sulphurlc acld (96X) and 20.0 cu m of hot water.
On completed preclpltatlon the pH of the suspenslon Is adJusted to a value of 3.5, usln3 concentrated sulphurlc acld (96X). The content of preclpltated slllca Is 66.0 g per lltre.
25 . 75 CU m of thls preclpltated slllca suspenslon are mlxed wlth 40.0 cu m of the suspenslon of a thlckenlng slllca content of 85.0 g per lltre correspondlng to a welght ratlo of 1:2 (relatlve to the solld content).
For the further treatment the procedure Is llke that In Example 1. The slllca content In the fllter press dough Is 21X.
The preclpltated slllca obtalned has the physlcal-chemlcal characterlstlc data complled In Table 1.
Examole ~
A preclpltated slllca low In Iron content Is pro-duced accordlng to Example 1 of D 47 633 (- DE-PS 12 93 !38)-18.5 lltres of water are put Into a cyllndrlcal, 30-lltre wooden tank provlded wlth a wooden blade mlxer (dlameter20 cm, helght 6 cm, 90 r.p.m.).
The water Is Indlrectly heated to 85C wlth an acld-proof steam-coll. In the recelver 25 g of sodlum fluorlde and 6.25 g of oxallc acld are dlssolved.
Whlle stlrrlng and malntalnlng a pH value of 2.0 5.45 lltres of a commerclal sodlum slllcate (molar ratlo of Na20:SlO2 1:3.36, denslty ~ - ,1.34) and 0.65 lltre of sul-phurlc acld 96% of H2SO4) were fed In wlthln 90 mlnutes at opposlte polnts.
Stlrrlng of the nascent suspenslon Is contlnued for approxlmately 30 mlnutes, followed by flIterlng on suctlon fllters In a conventlonal manner, uslng twlce the amount of 3 ~ ~ . ' t ~ .
water, relatlve to the volume of the suspenslon, wh I ch I S then washed, spray-drled and ground wlth an alr-Jet mlll.
Examcle 7 18.3 cu m of susPenslon of the abraslve slllca accordlng to Example 2 havlng a preclpltated slllca content of 92.0 g per lltre are then mlxed wlth 40.0 cu m of suspenslon of a preclpltated slllca low In Iron accordlng to Example 1 of D 47633 ~_ DE-PS 12 93 138) havlng a preclpltated slllca con-tent of 83.8 9 per lltre correspondlng to a welght ratlo of 1:2.
For the further treatment the procedure Is llke that In Example 3. The slllca content In the press dough Is 23%. -The preclpltated slllca obtalned has the physlcal-chemlcal characterlstlc data complled In Table 1.
ExamDle 8 For the productlon of a preclpltated slllca that Is low In Iron and has thlckenlng and cleanslng propertles the suspenslon of a low-lron content slllca produced accordlng to Example 1 of DE-PS 12 93 138 (- D 4763~3) Is mlxed In speclflc ratlos wlth the suspenslon of the abraslve slllca produced accordlng to Example 2. Table 2 shows that any welght ratlo the Iron content of the mlxture Is lower than that of the com-parable dry mlxture.
Table 2 Mlxture Ratlos In Parts by Welaht abraslve slllca as descrIbed 2 slllca low In Iron accordlng to Example 1 of D 47633 1 1 2 . _ 30wet mlxture ~ 157 p.p.m. 118 p.p.m. 80 p.p.m.
Fe Fe F~
1 3 ~
dry mlxture 168 p.p.m. 137 p.p.m. 101 p.p.m.
Fe Fe Fe ~ ~ o,~ c v;, ~ o FJ-- --n 1-ta ~ o o ~3 n u~ t~ ,p ~ ~
n 5'~ ~ e: Q ~ ' ~ ~
c ~ ~ n o l ~o tO1~ 0 ~ 1;
O dP ~ U) U~ r~ 1l_ ~a P O~ p p ~a ~ p ~ D p 0 P) n t~
~ 0 ~ ;1H ^ I Ul H
~ 0 ~
(D --t ~
3 n~ 3 ~ ~ 3 (o 3 W
n U~ O IC~ ~ O
1~1 tq N N ~ N W `0~ ~I 3 - O~ o~: N N Oo oo ~ 00 C0 ~ W ~ n .
O O ~ Ul W --~ O O , 00 0 ~11 W O ~D
W
~p, ~ o~ ~ x ~ O ~ W ~) N Ul Oo ~ 0~ ~ n 3 O O '~O O O O~ o ~ O O ~o O 'U .
` ` w ` ~ ~ ~
N O H. ~ oo ~ ~ oo ~ W ~ ~ ~ ~n X
rv o~ ~ o o o w o ~a ~D-.
w N ~ ~ O ~ I ~ ~ N ~ ~ n X
O O ,~ O O W r~ O u~ ~ O ~ n .3 ~ .
Xq N Ul ,~ ` W ~ ~ 0~ 0~ 3 ~ $ 1 Hl ~ ,~W~ o Oo O 00 W O r~
u~
~ W W W O~ N tq W 0 ~ N CO 0 ~ n ~3a ~n o o u~ ~ ~ o ~,n o o ~ o ~--$ ~ ID
3 0 a~
~ ~ N Xq ~D --I ~0 O ~ O W ~ ~O r A ~3a o o ~ n o ~ ~ o oo o ~ ~ n O I_ ~ I
1 3 w ~
The physl CA l-chemlcal characterlstlc data deflned In the present applIcatlon Are determlned as follows:
Loss on Drylng accordlng to DIN 53198.
Conductlvlty at 25C/4% suspenslon.
A sample of 4.0 g Is heated wlth 60 m/ of completoly fully desalted water In a 150 m/ beaker and bolled for one mlnute whlle stlrrlng. The suspenslon Is then transferred Into a 100 m/ flask, cooled and fllled up to the mark wlth completely full desalted water. The electrlc conductlvlty Is measured wlth a commerclal measurlng devlce, for example, of the "WlssenschaftlIche Werkstatten (WTW), conductlmeter type LF530, at 25C.
pH Value In a 6% dlsperslon accordlng to DIN 63200.
BET Surface Area accordlng to DIN 66131.
A sample Is rlnsed wlth nltrogen at 100C. The vol-umetrlc measurement Is carrled out wlth pure nltrogen at the temperature of the llquld nltrogen (-195.8C).
Tamped Denslty accordlng to DIN 53194.
The test Is carrled out wlthout pretreatlng the sample.
Macropore Volume D ~ 30 nm accordlng to ~he Hg pres-sure method.
The measurement Is carrled out wlth the Mercury Pressure Poroslmeter, 200 Serles of the flrm of Carlo Erba Strumentazlone.
OiI Absorptlon accordlng to Gardner-Coleman accord-lng to ASTM:D 1483-~0.
Water Retente Value.
The water retentlon value Indlcates the portlon of water contalned In the press dough upon squeezlng out preclpl-tated slllca suspenslon and washlng to a pauclty of elec-trolyte. For the computatlon 250 g of press dough are drled ~ 3 2 ..; ,. i i at 105C untll a constant welght Is attalned.
Computatlon - wel,ahed out X 100 100 - - X water retentlon value welghed sample.
Partlcle Slze Dlstrlbutlon accordlng to Coulter Counter/100~ caplllary.
The measurement Is carrled out wlth the Coulter Counter model TA I I of the flrm of Coulter Electronlcs GmbH.
Determlnatlon of the Cu Abraslon In a 10% Glycerol Dlsperslon:
a) Productlon of the alycerol Dlsperslon 153 g of glycerol (anhydrolcs, purest Ph Eur, BP USP, denslty 1.26 g~m/, fIrm of Merck, Darmstadt) are welghed Into a polyethylene beaker (250 m/). 17 g of preclpltated slllca are carefully Inter-mlxed wlth a spatula. The mlxture Is subsequently homogenlzed for 12 mlnutes wlth a blade agltator (dlameter 5.2 cm) at 1500 r . p . m .
b) Abraslon Measurlng Procedure The determlnatlon of the abraslon measurement Is carrled out In an abraslon testlng devlce, whlch Is known from followlng Publlcatlons (1) Pfungle: Fette, Selfen, Anstrlchmlttel, 63 (5) (1961), Page 445 to 4B1. "Abraslon und Relmgunskraft von Putz Korpern In Zahnpasten" (2) A. Reng, F. Danny; Parfumerle und Kosmetlk 59 (2) (197S), Page 37 to 45; "Anwendungstechmlsche Prufung von Zahnpasten". For thls purpose each of the slx troughs of the testIng devlce Is coated wlth 20 m/ of the homogeneous dlsperslon. The abraslon caused by slx surface-ground nylon brushes on slx surface-30 ~round Cu sheets (electrolyte-copper) In fIve hours wlth 50000 up and down strokes Is determlned by dlfferentlal welghlng.
When comPutlng the abraslvlty average values are formed from 1 ~ 2; ' `
the values obtalned. The abraslon (abraslvlty) Is deflned In mg of Cu.
RDA Abr~s I on .
The method Is descrlbed In Journal of Dental Research, 56(4), 663 (1976) and Is also applled to the REA
abraslon test.
REA Abras I on .
Scratches are determlned vlsually by means of a mlcroscope.
Determlnatlon of the Vlscoslty measured In a 16%
glycerol-water dlsperslon (mlxture 1:1) wlth a Brookfleld Vls-coslmeter RTV, splndle 10, wlth helIpath at 10 r.p.m.1. Test Mlxtures 48 g of slllca 126 g of glycerol (approxlmately 87%, purest Ph Eur. BP, den-slty ~ 1.26 g~m/ flrm of Merck, Darmstadt) 126 g of dlstllled water 300 g of a 16X dlsperslon, relatlve to slllca.
2. Procedure.
In a 400 m/ beaker glass (broad shape) the abraslve slllcas are stlrred by hand Into the glycerol-water mlxture wlth a glass rod (1 mlnute) and allowed to stand for Z4 hours. The vlscoslty Is measured thereafter.
3. Measurement.
The measurement of the vlscoslty Is carrled out In the same - ~ ~ dte~7a~k beaker wlth a Brookfleld-vlscoslmeter~ RVT, spindle 10 wlth helIpath at 10 r.p.m.
4. Computatlon.
Read scale value X factor vlscoslty In mPas.
_ 20 -
Read scale value X factor vlscoslty In mPas.
_ 20 -
Claims (6)
1. A precipitated silica having, the following physical-chemical features:
2. A process for the production of the precipitated silica as in claim 1, comprising:
(A) producing a thickened precipitated silica suspension by reaction of an alkali silicate solution with an acid while avoiding formation of a gel, in which the acid and the alkali silicate solution are fed into an aqueous alkali silicate solution reaction medium at selected solution concentrations and selected flow (Claim 2, con't. [Page 2]) velocities while maintaining a precipitation temperature of between 80°C. and 90°C. in the reaction medium to thereby precipitate silica, said reaction medium having an initial viscosity value, said aqueous alkali silicate solution reaction medium having a concentration of approximately 5 to 25 g of SiO2 per liter of solution, thereby holding the viscosity of the reaction medium uniformly low for a time period of at least 30% of the total precipitation time, and the pH of the reaction medium is held between 10 and 12, the viscosity of the reaction medium thereafter increasing as a result of the reaction up to a maximum value, terminating the feed of the reaction components before the viscosity of the reaction medium following passage through said maximum value has dropped to a point less than 100% above the initial viscosity, adding sulfuric acid to adjust the pH of the reaction medium to below 7, to thereby obtain a thickening precipitated silica, (B) producing an abrasive precipitated silica suspension by first precipitating silica from a selected alkali silica solution reaction medium with a concentration of about 5-25 g of SiO2 per liter solution, by adding to said solution reaction medium an acid and alkali metal silicate solution, while maintaining a precipitation temperature in the reaction medium of between 80°C. and 90°C., said reaction medium having an initial viscosity value, the viscosity of the reaction medium being uniformly low during a time period of at least 30% of the total precipitation time by control of addition of said acid and silicate solution, (Claim 2 con't. [Page 3]) maintaining the pH level between 10 and 12, terminating the addition of the acid and alkali silicate solution, before the viscosity of the reaction medium after passing through a maximum falls to a level less than 100%
above the initial voscosity, adjusting the pH level with sulfuric acid to 7 to 9, diluting with hot water to a precipitated silica content of 10-30 g/l and sodium sulfate content of 6-20 g of Na2SO4/1, heating to 80°C.-90°C., and while holding this pH level constant simultaneously adding alkali metal silicate solution, sulfuric acid and hot water, for a precipitation time of from 15 to 180 minutes, to obtain a precipitated silica final concentration of from 40 to 80 g/l, acidifying the suspension with sulfuric acid to a pH of below 7, mixing the two precipitated silica suspensions (A) and (B) thoroughly, and recovering a combined precipitated silica and then comminuting with an air jet mill.
(A) producing a thickened precipitated silica suspension by reaction of an alkali silicate solution with an acid while avoiding formation of a gel, in which the acid and the alkali silicate solution are fed into an aqueous alkali silicate solution reaction medium at selected solution concentrations and selected flow (Claim 2, con't. [Page 2]) velocities while maintaining a precipitation temperature of between 80°C. and 90°C. in the reaction medium to thereby precipitate silica, said reaction medium having an initial viscosity value, said aqueous alkali silicate solution reaction medium having a concentration of approximately 5 to 25 g of SiO2 per liter of solution, thereby holding the viscosity of the reaction medium uniformly low for a time period of at least 30% of the total precipitation time, and the pH of the reaction medium is held between 10 and 12, the viscosity of the reaction medium thereafter increasing as a result of the reaction up to a maximum value, terminating the feed of the reaction components before the viscosity of the reaction medium following passage through said maximum value has dropped to a point less than 100% above the initial viscosity, adding sulfuric acid to adjust the pH of the reaction medium to below 7, to thereby obtain a thickening precipitated silica, (B) producing an abrasive precipitated silica suspension by first precipitating silica from a selected alkali silica solution reaction medium with a concentration of about 5-25 g of SiO2 per liter solution, by adding to said solution reaction medium an acid and alkali metal silicate solution, while maintaining a precipitation temperature in the reaction medium of between 80°C. and 90°C., said reaction medium having an initial viscosity value, the viscosity of the reaction medium being uniformly low during a time period of at least 30% of the total precipitation time by control of addition of said acid and silicate solution, (Claim 2 con't. [Page 3]) maintaining the pH level between 10 and 12, terminating the addition of the acid and alkali silicate solution, before the viscosity of the reaction medium after passing through a maximum falls to a level less than 100%
above the initial voscosity, adjusting the pH level with sulfuric acid to 7 to 9, diluting with hot water to a precipitated silica content of 10-30 g/l and sodium sulfate content of 6-20 g of Na2SO4/1, heating to 80°C.-90°C., and while holding this pH level constant simultaneously adding alkali metal silicate solution, sulfuric acid and hot water, for a precipitation time of from 15 to 180 minutes, to obtain a precipitated silica final concentration of from 40 to 80 g/l, acidifying the suspension with sulfuric acid to a pH of below 7, mixing the two precipitated silica suspensions (A) and (B) thoroughly, and recovering a combined precipitated silica and then comminuting with an air jet mill.
3. The process of claim 2 wherein the two silica suspensions are mixed together in the ratio range of 1:2 to 2:1 based on the solids content.
4. The process of claim 2 wherein the acid is sulfuric acid and the alkali silicate is sodium silicate.
5. The process of claim 2 further comprising after mixing the two precipitated silicas, the resulting mixed silica is filtered out, washed, spray dried and comminuted in the air jet mill.
6. Use of a precipitated silica as defined in claim 1 as an abrasive or polishing medium in a toothpaste.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000616653A CA1331503C (en) | 1986-11-21 | 1993-05-04 | Precipitated silicas, process for producing same and their use |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3639845.4 | 1986-11-21 | ||
| DE19863639845 DE3639845A1 (en) | 1986-11-21 | 1986-11-21 | FELLING SILICS, METHOD FOR THE PRODUCTION AND USE THEREOF |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000616653A Division CA1331503C (en) | 1986-11-21 | 1993-05-04 | Precipitated silicas, process for producing same and their use |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1324247C true CA1324247C (en) | 1993-11-16 |
Family
ID=6314486
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000552383A Expired - Fee Related CA1324247C (en) | 1986-11-21 | 1987-11-20 | Precipitated silicas, process for producing same and their use |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US5110574A (en) |
| EP (1) | EP0272380B1 (en) |
| JP (3) | JPS63139014A (en) |
| AT (1) | ATE77939T1 (en) |
| CA (1) | CA1324247C (en) |
| DE (2) | DE3639845A1 (en) |
| DK (1) | DK172681B1 (en) |
| ES (1) | ES2033272T3 (en) |
Families Citing this family (33)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6143281A (en) * | 1987-03-31 | 2000-11-07 | Smithkline Beecham P.L.C. | Dentifrice compositions |
| DE59400684D1 (en) * | 1993-08-07 | 1996-10-24 | Degussa | Process for the preparation of a precipitated silica |
| US6977065B1 (en) * | 1993-10-07 | 2005-12-20 | Degussa Ag | Precipitated silicas |
| WO1996006593A1 (en) * | 1994-08-31 | 1996-03-07 | J.M. Huber Corporation | Cost effective dental compositions containing novel sodium aluminosilicates |
| ATE208607T1 (en) * | 1994-09-21 | 2001-11-15 | Crosfield Joseph & Sons | GRANULAR COMPOSITIONS |
| US5603920A (en) * | 1994-09-26 | 1997-02-18 | The Proctor & Gamble Company | Dentifrice compositions |
| US5846506A (en) * | 1994-10-07 | 1998-12-08 | Degussa Aktiengesellschaft | Precipitated silicas |
| US5571494A (en) * | 1995-01-20 | 1996-11-05 | J. M. Huber Corporation | Temperature-activated polysilicic acids |
| US5589160A (en) * | 1995-05-02 | 1996-12-31 | The Procter & Gamble Company | Dentifrice compositions |
| US5658553A (en) * | 1995-05-02 | 1997-08-19 | The Procter & Gamble Company | Dentifrice compositions |
| US5676932A (en) * | 1995-05-02 | 1997-10-14 | J.M. Huber Corporation | Silica abrasive compositions |
| US5651958A (en) * | 1995-05-02 | 1997-07-29 | The Procter & Gamble Company | Dentifrice compositions |
| DE69612977T2 (en) * | 1995-06-30 | 2001-09-06 | Crosfield Joseph & Sons | AMORPHE SILIC ACIDS AND ORAL COMPOSITIONS |
| DE19527278A1 (en) * | 1995-07-26 | 1997-01-30 | Degussa | Precipitated silica |
| US5891473A (en) * | 1995-09-09 | 1999-04-06 | Crosfield Limited | Granular Compositions |
| US5716601A (en) * | 1996-03-22 | 1998-02-10 | The Procter & Gamble Company | Dentifrice compositions |
| JP4235337B2 (en) * | 2000-03-02 | 2009-03-11 | 東ソー・シリカ株式会社 | Inkjet recording sheet filler |
| DE10112652A1 (en) * | 2001-03-16 | 2002-09-19 | Degussa | Inhomogeneous silicas for elastomer mixtures |
| DE10112650A1 (en) * | 2001-03-16 | 2002-09-19 | Degussa | Inhomogeneous silicas in dentifrices |
| DE10112651A1 (en) | 2001-03-16 | 2002-09-19 | Degussa | Inhomogeneous silicas as carrier material |
| US20060140877A1 (en) * | 2004-12-23 | 2006-06-29 | Mcgill Patrick D | Methods of producing improved cleaning abrasives for dentifrices |
| US20060140878A1 (en) * | 2004-12-23 | 2006-06-29 | Cornelius John M | Classified silica for improved cleaning and abrasion in dentifrices |
| CA2739041A1 (en) * | 2008-09-30 | 2010-04-08 | Evonik Degussa Gmbh | Production of solar-grade silicon from silicon dioxide |
| FR2984870B1 (en) * | 2011-12-23 | 2014-03-21 | Rhodia Operations | NEW PROCESS FOR THE PREPARATION OF PRECIPITED SILICES |
| MY180098A (en) * | 2011-12-23 | 2020-11-22 | Rhodia Operations | Novel process for preparing silicas |
| FR2985990B1 (en) | 2012-01-25 | 2014-11-28 | Rhodia Operations | NOVEL PROCESS FOR THE PREPARATION OF PRECIPITED SILICES WITH PARTICULAR MORPHOLOGY, GRANULOMETRY AND POROSITY |
| FR2985991B1 (en) | 2012-01-25 | 2014-11-28 | Rhodia Operations | NEW PROCESS FOR THE PREPARATION OF PRECIPITED SILICES |
| FR2985993B1 (en) * | 2012-01-25 | 2014-11-28 | Rhodia Operations | NEW PROCESS FOR THE PREPARATION OF PRECIPITED SILICES |
| JP2015504842A (en) * | 2013-01-23 | 2015-02-16 | ローディア オペレーションズ | Process for producing precipitated silica having unique morphology, particle size, and porosity |
| JP2015504843A (en) * | 2013-01-23 | 2015-02-16 | ローディア オペレーションズ | Method for producing precipitated silica |
| JP5868527B2 (en) * | 2013-01-23 | 2016-02-24 | ローディア オペレーションズ | Method for producing precipitated silica |
| EA202100032A3 (en) | 2020-02-21 | 2021-10-29 | Вингфлоу Аг | REACTOR FOR PRODUCING MICRONIZED SILICA GEL |
| EA202000367A1 (en) | 2020-02-21 | 2021-08-31 | Старк Свисс Аг | METHOD FOR PRODUCING MICRONIZED SILICA GEL |
Family Cites Families (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE629129A (en) * | 1962-03-02 | |||
| NL134071C (en) * | 1965-07-02 | |||
| US4001379A (en) * | 1968-04-27 | 1977-01-04 | Deutsche Gold- Und Silber-Scheideanstalt Vormals Roessler | Process of making superfine amorphous high structural silicic acid |
| US4003981A (en) * | 1968-04-27 | 1977-01-18 | Deutsche Gold- Und Silber-Scheideanstalt Vormals Roessler | Process of making superfine amorphous high structure silicic acid |
| GB1433743A (en) * | 1972-07-21 | 1976-04-28 | Unilever Ltd | Toothpastes |
| US3928541A (en) * | 1972-09-05 | 1975-12-23 | Huber Corp J M | Amorphous precipitated siliceous pigments for cosmetic or dentrifrice use and methods for their production |
| US3960586A (en) * | 1973-10-03 | 1976-06-01 | J. M. Huber Corporation | Amorphous precipitated siliceous pigments and improved process for producing such pigments |
| US4140757A (en) * | 1975-07-21 | 1979-02-20 | J. M. Huber Corporation | Extension of gum thickener with silicon dioxide and toothpaste containing the same |
| US4421527A (en) * | 1977-12-20 | 1983-12-20 | J. M. Huber Corporation | High fluoride compatibility dentifrice abrasives and compositions |
| US4340584A (en) * | 1978-09-28 | 1982-07-20 | J. M. Huber Corporation | Therapeutic dentifrices in unlined container and methods |
| FR2453880A1 (en) * | 1979-04-13 | 1980-11-07 | Rhone Poulenc Ind | NOVEL SILICA-BASED PIGMENT IN BALL FORM, PROCESS FOR OBTAINING THE SAME AND APPLICATION, IN PARTICULAR AS REINFORCING FILLER IN ELASTOMERS |
| US4420312A (en) * | 1979-05-23 | 1983-12-13 | J. M. Huber Corporation | Method for production of high fluoride compatibility dentifrice abrasives and compositions |
| US4356107A (en) * | 1979-11-26 | 1982-10-26 | Nalco Chemical Company | Process for preparing silica sols |
| DE3114493A1 (en) * | 1981-04-10 | 1982-10-28 | Degussa Ag, 6000 Frankfurt | "FELLING SILICONES AND METHOD FOR THE PRODUCTION THEREOF" |
| DE3144299A1 (en) * | 1981-11-07 | 1983-05-19 | Degussa Ag, 6000 Frankfurt | PELLETIC SILES WITH A HIGH STRUCTURE AND METHOD FOR THE PRODUCTION THEREOF |
| FR2562534B1 (en) * | 1984-04-06 | 1986-06-27 | Rhone Poulenc Chim Base | NOVEL PRECIPITATED SILICA WITH IMPROVED MORPHOLOGICAL CHARACTERS, PROCESS FOR OBTAINING THE SAME AND APPLICATION THEREOF, IN PARTICULAR AS FILLER |
-
1986
- 1986-11-21 DE DE19863639845 patent/DE3639845A1/en not_active Ceased
-
1987
- 1987-09-05 ES ES198787113004T patent/ES2033272T3/en not_active Expired - Lifetime
- 1987-09-05 DE DE8787113004T patent/DE3780279D1/en not_active Expired - Lifetime
- 1987-09-05 EP EP87113004A patent/EP0272380B1/en not_active Expired - Lifetime
- 1987-09-05 AT AT87113004T patent/ATE77939T1/en not_active IP Right Cessation
- 1987-11-13 DK DK198705964A patent/DK172681B1/en active
- 1987-11-19 JP JP62290795A patent/JPS63139014A/en active Granted
- 1987-11-20 CA CA000552383A patent/CA1324247C/en not_active Expired - Fee Related
-
1988
- 1988-12-07 US US07/281,917 patent/US5110574A/en not_active Expired - Fee Related
-
1993
- 1993-01-28 JP JP5012402A patent/JP2690439B2/en not_active Expired - Lifetime
- 1993-01-28 JP JP5012400A patent/JP2690438B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| DK596487D0 (en) | 1987-11-13 |
| JPS63139014A (en) | 1988-06-10 |
| ATE77939T1 (en) | 1992-07-15 |
| JPH06107410A (en) | 1994-04-19 |
| DE3639845A1 (en) | 1988-06-01 |
| EP0272380A2 (en) | 1988-06-29 |
| DE3780279D1 (en) | 1992-08-13 |
| DK596487A (en) | 1988-05-22 |
| JP2690438B2 (en) | 1997-12-10 |
| JPH06107409A (en) | 1994-04-19 |
| DK172681B1 (en) | 1999-05-25 |
| JP2690439B2 (en) | 1997-12-10 |
| JPH0549607B2 (en) | 1993-07-26 |
| EP0272380B1 (en) | 1992-07-08 |
| US5110574A (en) | 1992-05-05 |
| EP0272380A3 (en) | 1989-05-03 |
| ES2033272T3 (en) | 1993-03-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1324247C (en) | Precipitated silicas, process for producing same and their use | |
| US5124143A (en) | Dentrifice | |
| JP2556667B2 (en) | Method for producing precipitated silica | |
| CA1093789A (en) | Precipitated siliceous products and methods for their use and production | |
| US3928541A (en) | Amorphous precipitated siliceous pigments for cosmetic or dentrifrice use and methods for their production | |
| US4857289A (en) | Process for preparing precipitated silica | |
| AU730648B2 (en) | Silica which can be used in toothpaste compositions | |
| EP0495039B1 (en) | Silicas | |
| JPH02237910A (en) | Silica for tooth paste component espacially with compatible with zinc | |
| AU2001277184A1 (en) | Method for making abrasive compositions and products thereof | |
| WO1997012843A1 (en) | Microporous high structure precipitated silicas and methods | |
| EP1773948A1 (en) | Method for making precipitated silicate compositions and products thereof | |
| MXPA06006866A (en) | Highly-structured silica having a low water uptake, preparation method thereof and uses of same. | |
| KR950006634B1 (en) | Silica its process of manufacture and especially the use as fillers for paper | |
| US4038098A (en) | Amorphous precipitated siliceous pigments for cosmetic or dentrifice use and methods for their production | |
| JP3594615B2 (en) | Small particle size P-type zeolite | |
| JP2002338233A (en) | Silicic acid, method for preparation the same and use thereof in tooth mending agent | |
| CA1331503C (en) | Precipitated silicas, process for producing same and their use | |
| JPS60158108A (en) | Dialytic silica dentifrice | |
| JP2001072409A (en) | Production of high-purity silica gel and its use | |
| US20090196929A1 (en) | Silica Wetcake Treatment Method | |
| KR100503705B1 (en) | Silica capable of being used in toothpaste compositions | |
| US20050158225A1 (en) | Structure level of silica from silica slurry method | |
| JPH0413613A (en) | Dentifrice composition silica miscible particularly organic amino compound | |
| MXPA98008481A (en) | Composition of tooth paste comprising an abrasive or additive based silicone and carbonate decalcio, compatible with fl |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |